The present disclosure relates to a sheet storage cassette that stores sheet-like recording mediums such as paper sheets and the like used in a copy machine, a printer, a facsimile, a multi-function machine of them and the like and to an image forming apparatus that includes the sheet storage cassette.
A sheet feeding cassette, which stores a plurality of sheets (paper sheets), is disposed in a drawable manner on a bottom portion of a main body of an image forming apparatus; a separating and feeding device composed of a pick-up roller and the like disposed above the sheet feeding cassette sends out successively the sheets stored in the sheet feeding cassette one after another, and a conveyance roller conveys the sheets to an image forming portion and a fixing portion, whereby an image is formed on the sheets.
There are sheet feeding cassettes in which a cassette base, which stores sheets in accordance with sheet sizes such as an A-system size, a B-system size, an inch-system size and the like, is composed in a stretchable and shrinkable manner. Here, because of a need for compactness of an image forming apparatus in recent years, there is a case where the area of the sheet feeding cassette becomes larger than the area of a main body of the image forming apparatus. In such a case, a portion of the sheet feeding cassette protrudes from the main body of the image forming apparatus; accordingly, there is a risk that foreign matter such as dust and the like would enter the sheet feeding cassette from the protruding portion.
Because of this, a sheet feeding cassette is known, in which an upper-surface cover is disposed on the cassette base to prevent foreign matter from entering.
In a case where the upper-surface cover is mounted swingably on the cassette base, generally, bosses (or engagement holes) formed at two pivots of the cassette base are press-fitted into two engagement holes (or bosses) formed at two pivots of the upper-surface cover. Here, considering assembly efficiency, an engagement amount of the boss and the engagement hole is made large at one rotation fulcrum, while an engagement amount of the boss and the engagement hole is made small at the other rotation fulcrum, and the engagement portion having the smaller engagement amount is bent to perform press-fitting.